Structure and Function of Cells and Organelles

A cell is a small membrane enclosed structure filled with an aqueous solution where the organelles are found. Organelles are small structures within cells that perform dedicated functions. All eukaryotic cells have the following organelles: Nucleus, Ribosomes, Lysosomes, Cytoplasm, Nucleolus, Cell Membrane, Mitochondria, Endoplasmic Reticulum (ER) and Golgi Body. Insulin is a protein compound made up of more than one chain of amino acids. Amino acids are the building blocks of protein and it is these that determine the structure and function of proteins. Insulin is made within the pancreas where there are clusters of specialised cells called the islets of Langerhans. A type of cell within the islets is the pancreatic beta cell and this is where insulin is made, stored and secreted. To enable the cells to be able to produce the insulin ATP energy is required.

1. Website Image of Beta Cell - http://www.pharmabase.org Mitochondria are the organelles that make the molecules that provide the cell energy called Adenosine Tri phosphate (ATP). One of these organelles is a mitrochondrion which means threadlike granule. The mitochondria organelles are surrounded by a special bilayer membrane, this membrane controls substances moving in and out. The inner membrane folds are called cristae. There function is to increase the surface area on which the final stage of aerobic respirations take place. Inside the inner membrane is the matrix containing enzymes, a circular DNA molecule and ribosomes. 2. Website Image of Structure of Mitochondria - http://www.tutorvista.comInsulin is produced in stages and begins in the ribosomes on the Rough Endoplasmic Reticulum (RER). Ribosomes are small granules found in all cells and are made up of one large and one small subunit and comprise of rRNA. This is the only organelle not made from membranes. The ribosomes job is to...

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...CELLSTRUCTURE AND FUNCTOIN
* The Cell Theories 3 major principles:
* Cell is the basic unit of life
* All organisms consist of one or more cells
* New cells are created when existing cells divide
* Most cells contain 4 common features:
* A flexible plasma membrane that surrounds the cell
* A thick fluid called cytosol that fills their interior
* The nucleic acid DNA
* Protein structures called ribosomes, which are responsible for making other proteins important for various cellfunctions
* Plasma membranes:
* Consist of a phospholipid bilayer-
* Two layers of phospholipids arranged so that the hydrophilic
heads” in each layer face outwards
* Are fluid: phospholipids are able to move, usually side to side, within a layer
* Plasma membranes contain many other macromolecules:
* A variety of proteins, lipids, and carbohydrates are embedded in a plasma membrane
* Proteins have many functions in the membranes:
* Channels that help the passage of ions or molecules
* Enzymes, which control chemical reactions
* Anchors for other cellstructures, such as the cytoskeleton
* Receptors, which bind molecular signals that are important for...

...nucleus is the most obvious organelle in any eukaryotic cell. It is enclosed in a double membrane and communicates with the surrounding cytosol via numerous nuclear pores. Within the nucleus is the DNA responsible for providing the cell with its unique characteristics. The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off - that's why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell. When a cell is dividing, the nuclear chromatin (DNA and surrounding protein) condenses into chromosomes that are easily seen by microscopy.
Nucleolus: The prominent structure in the nucleus is the nucleolus. The nucleolus produces ribosomes, which move out of the nucleus and take positions on the rough endoplasmic reticulum where they are critical in protein synthesis.
Cytosol: The cytosol is the "soup" within which all the other cellorganelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors.
Cytoplasm: This is a collective term for the cytosol plus the organelles suspended within...

...Structure and Function of Eukaryotic CellOrganelles
What are eukaryotic and prokaryotic cells?
Organelles in Eukaryotic Cells
The Nucleus.
Nearly all animal cells have a nucleus, with the only exception being the red blood cell. The nucleus has two major functions, which are housing the DNA and controlling the cell’s activities. In the centre of the nucleus is the nucleolus. This doesn’t have a membrane, but holds itself together. In the nucleolus, ribosomes are created through the mixture of RNA and proteins. These proteins are originally found in the cytoplasm, outside the nucleus, but they travel through the pores in the nuclear envelope, through the chromatin and into the nucleolus. The structure of the nucleolus allows easy access for the proteins, as well as an easy exit for the ribosome subunits. The chromatin that surrounds the nucleolus contains both DNA and proteins. When the cell is dividing the chromatin, which is a mess of DNA strands, start to curl. After they have finished curling you can see clear, organised chromosomes. The cell divides when each of these chromosomes replicates itself through mitosis. On the outside of the nucleus is the nuclear envelope. This is a double layered membrane which holds together the contents of the nucleus, and is attached to the rough...

...Each cell can be regarded as a metabolic compartment, as separate place where the chemical processes of that cell occur, the cell is made up of different organelles each specifically designed to carry out their function, and this is known as a cells ultrastrucure.
All cells have a cell surface membrane; these are made up of phospholipids and make up a bilayer. A phospholipid has a hydrophilic head and a hydrophobic tail which is made up of 2 fatty acid chains; these are arranged is two layers with the tails facing inwards. Lipids soluble material can move through the plasma membrane but water soluble substance are unable to pass and therefore protein ion channels are required to monitor the inward and outward movement of these substances. This bilayer that surrounds the cell can be described as a fluid mosaic model, fluid because the molecules are still able to move allowing the cell to have a flexible shape and mosaic because the proteins embedded in the membrane are all different sizes shapes and pattern.
The nucleus is the most prominent feature if a eukaryotic cell, it controls the cell’s activities and contains the organisms hereditary material. The nucleus is made up of a number of parts; the nuclear envelope is a double membrane that continues with the endoplasmic reticulum, it controls the entry and exit of...

...Plant CellOrganelles Description
Organelle Description
Nucleus The nucleus contains all of the genetic make-up of the cell and is the control center of the cell
Nucleolus The nucleolus is inside the nucleus and has the job of producing ribosomes
Cytosol Contains all of the cell’s organelles
Centrosome Produces Microtubules, helps in cell division
Microtubules The migration of chromosomes in mitosis and meiosis takes place on microtubules that make up the spindle fibers
Golgi Apparatus Has the job of “packaging” the organelles to be sent throughout the cell
Lysosome Lysosomes are rare in plant cells but have the job of cleaning up in the cell
Peroxisome Convert fatty acids into sugar and assist the chloroplast in photorespiration
Secretory Vesicle Packages hormones, neurotransmitters, etc. then are transported to the cell surface for release
Cell Membrane Has a phospholipid bilayer with hydrophilic heads and hydrophobic tails, the membrane also contains protein, making it semi-permeable
Mitochondrion Provide the energy the cell needs to move, divide, contract, etc. They are the power house of the cell.
Vacuole Very large in plant cells. Store nutrients and waste products, help increase size of cell during growth, and act...

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BIOLOGY 12- CELLSTRUCTURE & FUNCTION Chapter Notes
THE CELL THEORY
• Although different living things may be as unlike as a violet and an octopus,
they are all built in essentially the same way. The most basic similarity is that
all living things are composed of one or more cells. This is known as the
Cell Theory.
• our knowledge of cells is built on work done with microscopes
• English scientist Robert Hooke in 1665 first described cells from his
observations of cork slices. Hooke first used the word “cell”.
• Dutch amateur scientist Antonie van Leeuwenhoek discovered microscopic
animals in water
• German scientists Schleiden and Schwann in 1830’s were first to say that all
organisms are made of one or more cells.
• German biologist Virchow in 1858 stated that all cells come from the division of pre-existing cells.
• Cells are the building blocks of life.
The Cell Theory can be summarized as:
1. All living organisms are made up of one or more
2. The cell is the basic of life
3. All cells come from the of pre-existing cells
• cells come in many shapes and sizes, although most are microscopic:
o Most cells are small, about 0.001 cm in length (1/100 of a mm, or 10 μm).
o the...

...Babin Ms. Bukola
11/6/2012 Bio Lab W 8
CellStructure and Function
Prokaryotic cells do not contain a nucleus. Eukaryotic cells do contain a nucleus. Organisms are eukaryotic except Bacteria and Achaea. Organelles are small membranous bodies, each with a specific structure and function. Prokaryotes do have cytoplasm, which is the material bounded by a plasma membrane and cell wall. This contains ribosomes, small granules that coordinate the synthesis of proteins. Prokaryotes also have a nucleoid which is the inner interior of the cell where the DNA is organized and stored but not enclosed by the membrane.
Prokaryotic cells lack membrane-bounded organelles as well as a nucleus. Their DNA is in a nucleoid region. The prokaryotic cell consists of a fimbriae, flagellum, ribosome, nucleoid, plasma membrane, cell wall, and capsule. The fimbriae is hair-like bristles that allow adhesion to the surfaces. The flagellum is rotating filament present in some bacteria that pushes the cell forward. Ribosomes are the site of protein synthesis. The nucleoid is the location of the bacterial chromosome. The plasma membrane is the main entrance and exit of molecules thru the cell. The cell wall covers, protects, supports...